Project Summary The overall goal of the proposed research is to determine the light encoding properties of two classes of amacrine cell in the primate retina: wiry-type and starburst cells. Despite the tremendous advances in the study of cell types and circuits in the mammalian retina, essentially nothing is known of the function of amacrine cells in the primate retina. The first recordings will be performed from wiry-type and starburst amacrine cells in an in vitro preparation of the macaque monkey retina. The proposed research has two specific aims: 1) To determine the light encoding and intrinsic properties of wiry-type amacrine cells in the primate retina. I will make the first recordings of identified wiry-type amacrine cells in the primate retina and use motion stimuli and spatio-temporal white noise to measure the encoding properties of these cells. I will test the specific hypotheses (A) that wiry- type cells prefer local motion to global motion, (B) that voltage-gated sodium channels contribute to signal propagation in their dendrites, and (C) that wiry-type cells are GABAergic. 2) To determine whether primate starburst amacrine cells show direction selectivity. I will make the first recordings of identified starburst amacrine cells in the primate retina and use motion stimuli and spatial noise to determine directly whether primate starburst cells are direction selective. I will specifically test the hypotheses (A) that primate starburst cells show direction selectivity, preferring centrifugal motion and (B) that starburst cells in the primate and mouse show similar light encoding properties.